Hermetically-sealed dry ceij



r/qj z Filed June 21. 1921 H D BATCHELOR HERMETICALLY SEALED DRY CELLAug. 26 1924.

Patented Aug. 26, 1924.

UNITED STATES PATENT OFFICE.

HARRY D. BATCHELOR, OF NEW YORK, N. Y., ASSIGNOB. TO NATIONAL CARBONCOMPANY, INC., A CORPORATION OF NEW YORK.

HEBMETICALLY-SEALED DRY CELL.

Application filed June 21, 1921. Serial No. 479,287.

T all whom it may concern:

Be it known that I, HARRY D. Bn'ronnnon, a citizen of the United States,residing at New York. in the county of New York and State of New York,have invented certain new and useful Improvements in Hermetically-SealedDry Cells, of which the following is a specification.

This invention relates to dry cells and has particular reference tomeans for sealing such cells in a manner to prevent the passage of Watervapor or gases, together with means for dissipating gaseous pressurewithin the cell.

It is generally accepted that the deterioration which dry cells undergoduring the period before they are put into use is due in part to theslow escape of moisture through crevices between the seal and theelectrodes, or through the pores of the carbon pole. This results in aprogressive diminishing of the quantity of electrolyte solution and inshrinkage of the mix bobbin or bibulous lining, thus materiallyincreasing the internal resistance of the cell and eventually renderingit inoperative. It is probably true, also, that wasteful electrolyticaction in the cell is facilitated by the entrance of air through theopenings referred to. Due to the alternat ing contraction and expansionof the gaseous contents of the cell under varying atmospherictemperature conditions, appreciable amounts of air may be caused toenter the cell. The oxygen so introduced may depolarize the minutevoltaic couples set up between the zinc and its impurities in thepresence of electrolyte, and so permit the destructive electrochemicalaction to continue.

For these and other reasons, the desirability of hermetically sealingdry cells has been recognized, but it has heretoforeheen regarded asimpractical because of internal gaseous pressure. It is well known thatgases produced by local action, decomposition of the mix or othercauses, collect within the cell and may eventually attain sufficientpressure to bulge and rupture the seal or zinc cup, unless an opening ofsome sort is provided for their escape.

The object of my invention is to provide a hermetic seal containing amaterial capable of taking up the gases evolved during the pro-servicelife of the cell. This object is attained by enclosing the up er end ofthe cell in an imprevious ca'p sea ed to the zinc container in suchmanner as to be easily removable when the cell is to be used, and packedwith a material capable of fixing the gases evolved. The material may bean absorbent or adsorbent substance and is preferably activated carbon.

The invention will be described in detail in connection with theaccompanying drawing, in which Fig. l is a vertical longitudinal sectionthrough a dry cell provided with a hermeticaldly sealed cap packed withan adsorbent, an

Fig. 2 is a fragmentary side elevation showing the removable sealingmeans.

Reference numeral 1 denotes a zinc container, 2 a lining of bibulousmaterial and 3 a mix bobbin containing a carbon rod 4. The zinccontainer has a marginal depression 5 to which a binding post may beattached so as to lie wholly within the outline of the container. Aplastic seal 6 of the usual type is provided. This seal is nonhermeticbut is sufficiently close fitting to prevent undue evaporation ofmoisture after the removal of the absolutely air-tight clo sure now tobe described.

The hermetic seal comprises a cap 7, of metal or other imperviousmaterial, having a cross section corresponding to that of the container31. The cap and container, placed with their margins in abuttingrelation, are secured together by means of a band 8 overlying theirjunction. The band 8 may be attached in any manner which will give a secure and air-tight joint, as, for example, by soldering it to both theca and container. A tongue 9 is provided on t e band 8 and is adapted tobe passed through an opening 10 in key ll. When it is desired to removethe hermetic sealing cap 7, the band may be severed by engaging thetongue in the key and rotating the latter to tear the metal along thelines of the sides of the ton ue extended, in a well known manner. A c'p 12 may be provided on the to of cap 7, or elsewhere on the cell, forholding the key in handy position.

The cap 7 contains a body of absorptive material 13, such as activatedcharcoal, spaced from the carbon electrode and its binding post by aninverted cupped insulating sheet 14, charcoal may known or suitable ofpaper or the like. The prepared in any well may and will of course befilled into the cap 7 and placed in operative %osition without unduecontact with the air.

ases evolved within the cell may pass through crevices between theplastic seal 6 and the electrodes, or through pores in the carbon rodand insulating sheet 14, into contact with the aborbent.

Unactivated charcoal and numerous other materials, as well as activatedcharcoal, are known to have the power to absorb relatively large volumesof gas. For the purposes of this invention, the mechanism of this actionis relatively unimportant and the term absorption will be understood tobe generic to adsorption, occlusion or the like. Any efficient absorbingmaterial may be used. I prefer, however, to use activated charcoal, asthe highly absorbent character of this substance makes it possible tosupply sufficient material for taking up substantially all of the gasgenerated in the cell without unduly adding to its bulk, even where thecell is allowed to retain its hermetic seal for long periods. When thecell is to be put into service, the cap 7 will be removed as described,together with the insulating sheet 14:. The service characteristics ofcells so protected from the deleterious effects of loss of moisture,access of oxygen, or other causes due to incomplete isolation from theatmosphere, will be found substantially equal to those of freshlyprepared cells.

It would of course be possible to supply sufficient absorbent to take upgases generated also during the active period of the cells life, and insuch case the hermetic seal would be retained, the connecting wiresbeing brought out in any suitable air-tight manner. T he shape and modeof attachment of the sealing cap may also be modified to fit it for usewith cells of non-cylindrical type, and various other changes inconstruction and relative arrangement of parts may be made within thescope of the appended claims.

I claim:

1. In a dry cell, means independent of the depolarizer for fixing gasesevolved in said cell.

2. A hermetically sealed dry cell containing a material capable ofabsorbing gases evolved in said cell.

3. A hermetically sealed dry cell containinga carbonaceous materialcapable of absorbing gases evolved in said cell.

l. A hermetically sealed dry cell containing activated carbon disposedso as to take up gases evolved in said cell.

5. In a dry cell, a seal adapted to permit the passage of gasesgenerated in the cell, a body of gas absorbing material upon said seal,and an air-tight cap about said material and engaging the wall of thecell.

6. In a dry cell, a cap hermetically sealing the cell and containing agas absorbing material, and means for removing the cap.

In testimony whereof, I afiix my signature.

HARRY D. BATCHELOR.

